#include <bits/stdc++.h>
using namespace std;
struct gold{
    int m, v;
    double money;
}a[105];
bool cmp(gold x, gold y){
    return x.money > y.money;
}
int main(){
    int n, t;
    cin >> n >> t;
    for (int i = 0; i < n; i++){
        cin >> a[i].m >> a[i].v;
        a[i].money = 1.0 * a[i].v / a[i].m;
    }
    sort(a, a + n, cmp);
    int mark = 0;
    double ans = 0;
    while (t >= a[mark].m && mark < n){
        t -= a[mark].m;
        ans += a[mark].v;
        mark++;
    }
    ans += t * a[mark].money;
    printf("%.2f", ans);
    return 0;
}